The present invention relates generally to bending method and bending system and more particularly to bending method and bending system achieved by taking into account a spring back and elongation which accompany bending.
Conventionally, when a sheet material is bent, generally, a bending angle of the sheet material W is measured to confirm a processing accuracy. That is, if a bending load is removed from the sheet material W being bent, the sheet material W is returned to its original shape due to a spring back as shown in FIG. 1. Thus, if the bending angle does not reach its object angle, corrective bending is further carried out so as to carry out correction. The spring back amount can be obtained from a difference in the angle of the workpiece W between before and after the load is removed.
As for measurement of the bending angle, according to a non-contact type measurement method shown in FIG. 2, light L is projected to the sheet material W bent by cooperation of a punch P and die D and then its reflected light is received to measure a bending angle. Alternatively, according to another method, as shown in FIG. 3, an indicator 101 is brought into contact with the bent flange of the sheet material W and the bending angle is measured based on a moving amount of the indicator 101.
However, according to these conventional technologies, upon actual bending operation, a corrective bending must be carried out with measurement of the bending angle and to achieve an accurate bending, the corrective bending must be executed repeatedly, thereby necessitating much time and labor.
Further, sometimes, when the sheet material is bent, an elongation may occur, so that the bending cannot be carried out with accurate dimension.
The present invention has been achieved in views of the above described conventional technologies, and an object of the invention is to provide a bending method and bending system capable of carrying out bending with a highly accurate bending angle and dimension without executing the corrective bending repeatedly.
According to an aspect of the resent invention, there is provided a bending method that includes the following steps (1) to (10):
(1) step of creating a three-dimensional stereoscopic diagram through an expansion plan based on graphic information of a product;
(2) step of displaying a ma or dimension and a tolerance in the three-dimensional stereoscopic diagram created in the step (1);
(3) step of displaying a test piece manufactured preliminarily of the same material as that for use in manufacturing the product;
(4) step of carrying out trial bending on the test piece displayed in the step (3) and measuring a bending angle before load removal;
(5) step of measuring a bending angle after a load is removed in the trial bending of the step (4) and measuring an elongation amount of flange width due to the bending;
(6) step of calculating a s ring back amount from a bending angle before the load is removed of the step
(4) and a bending angle after the load is removed of the step (5);
(7) step of obtaining an object D value from the spring back amount of the step (6) and obtaining an object L value from the elongation amount of the step (5);
(8) step of carrying out actual bending based on the object D value and the object value;
(9) step of measuring a bending angle and a flange width after a load for the actual bending of the step (8) is removed and determining whether or not the measured angle and the measured flange width are within tolerances relative to an object angle and an object flange width; and
(10) step in which if it is determined that the measured angle and the measured flange width are within the tolerances in the step (9), the bending is terminated; and if it is determined that the measured angle and the measured flange width are not within the tolerances, a correction value D is obtained from a difference between the object bending angle and an actual bending angle; a correction L value is obtained from a difference between the object flange width and an actual bending flange width; corrective bending is carried out according to the correction D value and correction L value; the processing is returned to the step (9); and accordingly the steps (9) and (10) are repeated.
Therefore, the three-dimensional stereoscopic diagram is produced from the product graphic information and at the same time, the major dimension and the tolerance are displayed on this three-dimensional stereoscopic diagram. On the other hand, the test piece is produced preliminarily of the same material as that for use in producing a product and this test piece is displayed and bent for trail so as to obtain a spring back amount and an elongation amount of a flange dimension. Because the test piece is manufactured of the same material as the final product, the spring back amount and the elongation amount of the flange obtained from the trial bending are the same as those obtained in an actual bending on the product. Thus, an object D value for the stroke in the actual bending and an object L value for the back gauge position are set up considering the spring back amount and the elongation amount of the flange obtained as a result of the trial bending so as to carry out the actual bending. The bending angle and flange dimension in the actual bending are measured. If they are not within tolerances relative to the object bending angle and the object flange dimension, the correction D value and correction L value are calculated to carry out the corrective bending. This procedure is repeated until they fall within the tolerances.
According to another aspect of the present invention, there is provided a bending method that includes the following steps. (1) to (9):
(1) step of creating a three-dimensional stereoscopic diagram through an expansion plan based on graphic information of a product;
(2) step of displaying a major dimension and a tolerance in the three-dimensional stereoscopic diagram created in the step (1);
(3) step of displaying a test piece manufactured preliminarily of the same material as that for use in manufacturing the product;
(4) step of bending the test piece displayed in the step (3) for trial based on a spring back amount and an elongation amount obtained preliminarily under various processing conditions;
(5) step of measuring a bending angle and a flange dimension of the test piece bent in the step (4) after a load is removed and then comparing the bending angle and the flange dimension with their object values;
(6) step of calculating an object D value and an object L value considering a difference between object values and measured values and various attributes;
(7) step of carrying out actual bending based on the object D value and the object value;
(8) step of measuring a bending angle and a flange width after a load for the actual bending of the step (7) is removed and determining whether or not the measured bending angle and the measured flange width are within tolerances relative to an object bending angle and an object flange; and
(9) step in which if it is determined that the measured bending angle and the measured flange width are within the tolerances in the step (8), the bending is terminated; and if it is determined that the measured bending angle and the measured flange width are not within the tolerances, a correction value D is obtained from a difference between the object bending angle and an actual bending angle; a correction L value is obtained from a difference between the object flange width and an actual bending flange width so as to be stored in a data base; corrective bending is carried out according to the correction D value and the correction L value; the processing is returned to the step (9); and accordingly the steps (9) and (10) are repeated.
Therefore, the three-dimensional stereoscopic diagram is produced based on the product graphic information and at the same time, the major dimension and the tolerance are displayed in this three-dimensional stereoscopic diagram. On the other hand, a spring back amount and an elongation amount in the flange dimension are obtained preliminarily under various processing conditions for the test piece produced of the same material as that for use in producing the final product. The object D value of the stroke and the object L value of the back gauge position are set up considering these preliminarily obtained spring back amount and elongation amount in the flange dimension and then trial bending is carried out. Because the test piece is produced of the same material as the product, it is considered that the preliminarily obtained spring back amount and elongation amount in the flange are the same as those in the actual bending on the product. Therefore, the bending angle and the flange dimension in the actual bending are measured and then, the object D value and object L value are calculated considering a difference between the object bending angle and object flange dimension and various processing conditions so as to carry out the actual bending. After the actual bending, the bending angle is measured and if the measured angle is not within the tolerance, the correction D value and correction L value are calculated and the corrective bending is carried out. Then, this procedure is repeated until they fall within the aforementioned tolerances.
According to still another aspect of the present invention, there is provided a bending method for bending both sides of a major dimension portion of a workpiece to form flanges, wherein a dimension of one bent flange is measured; if the measured value is over an object value, an object L value in the other flange processing is set to be below a flange dimension by a predetermined value; if the measured value is below the object value, the object L value in the other flange processing is set to be over the flange dimension by a predetermined value; and then bending is carried out with the set object L value.
Therefore, when both sides of the major dimension portion of a workpiece are bent to form flanges, first of all, one flange is formed by bending and then its flange dimension is measured. If the measured value is over an object value, an object L value that set the other flange dimension shorter is calculated. If the measured value is below the object value, an object L value that set the other flange dimension longer is calculated and then the bending is carried out.
According to yet another aspect of the present invention, there is provided a bending method for bending both sides of a major dimension portion of a workpiece to form flanges, wherein a dimension of one bent flange is measured; and when a dimension of said major dimension portion is within a tolerance if a dimension of the other flange is the same as the dimension of said one bent flange, the workpiece is inverted and then subjected to bending with the same L value.
Thus, when both sides of the major dimension portion of the workpiece are bent to form flanges, first of all, one flange is formed by bending and is flange dimension is measured. When a dimension of said major dimension portion is within a tolerance if a dimension of the other flange is the same as the dimension of said one bent flange, the workpiece is inverted and then subjected to bending with the same L value.
According to an aspect of the present invention, there is provided a bending method for bending both sides of a major dimension portion of a work piece to form flanges, wherein a dimension of one bent flange is measured; and if the measured value is within a tolerance, a dimension of said major dimension portion is assumed to be an object L value and said one bent flange is brought into contact with end gauges for bending.
Thus, if the dimension of one bent flange is within the tolerance, the object L value is set up with respect to the major dimension portion and then the bending is carried out.
Further, to achieve the above object, according to another aspect of the present invention, there is provided a bending system for manufacturing a product by bending a sheet material by means of a bending machine, including: three-dimensional stereoscopic diagram creating means for creating a three-dimensional stereoscopic diagram through an expansion plan based on graphic information of the product; major dimension display means for displaying a major dimension in the three-dimensional stereoscopic diagram created by the three-dimensional stereoscopic diagram creating means; test piece display means for displaying the test piece manufactured preliminarily of the same material as material for use in producing the product; a bending angle measuring device for measuring bending angles of the test piece bent by the bending machine and the product; spring back amount setting means for setting a spring back amount for the test piece; and object stroke calculating means for calculating an object D value corresponding to an object bending angle of actual bending for the product considering the spring back amount obtained by the spring back amount setting means.
Thus, the three-dimensional stereoscopic diagram creating means produces the three-dimensional stereoscopic diagram based on the product graphic information and the major dimension display means displays the major dimension, tolerance and the like in this three-dimensional stereoscopic diagram. On the other and, the test piece display means displays the test piece manufactured preliminarily of the same material as that for use in producing the product. By bending this test piece for trial, the bending angle measuring device measures the bending angles before and after the bending load is removed (before and after the load removal). The object stroke calculating means calculates the object D value relative to the object bending angle considering the spring back amount set by the spring back amount setting means and carries out the actual bending.
According to still another aspect of the present invention, there is provided a bending system wherein the spring back amount setting means calculates the spring back amount from a difference in bending angle between before and after a load on the test piece is removed, the bending angle being measured by the angle measuring device.
Thus, the bending angles before and after the load on the test piece for the trial bending is removed are measured and the spring back amount is calculated from the difference.
According to yet another aspect of the present invention, there is provided a bending system wherein the spring back amount setting means includes a data base for storing the spring back amounts for the test piece corresponding to various processing conditions, the spring back amounts being preliminarily obtained.
Therefore, the spring back amount for a test piece to be subjected to the trail bending is set up based on the spring back amount stored in the database corresponding to various processing conditions.
According to an aspect of the present invention, a bending system also includes a flange dimension measuring device for measuring a flange dimension of the test piece bent for trial; and an object L value calculating means for calculating an object L value corresponding to an object flange dimension in actual bending considering an elongation of the flange measured by the flange dimension measuring device.
Therefore, the flange dimension measuring device measures the flange dimension of the test piece bent for trial to obtain the elongation amount. Considering this elongation amount, the object L value calculating means calculates the object L value with respect to the object flange dimension.
According to still another aspect of the present invention, a bending system includes correction value calculating means for setting a correction D value for corrective bending to be carried out if a bending angle after the load for actual bending is removed, measured by the bending angle measuring device is not within a tolerance relative to the object bending angle, so as to put the measured bending angle within the tolerance.
Thus, if the bending angle in the actual bending is not within the tolerance which is a permissible range relative to the object bending angle, the correction value calculating means sets up the correction D value and carries out the corrective bending.
According to still another aspect of the present invention, a bending system also includes correction value calculating means for setting a correction L value for corrective bending to be carried out if a flange dimension after the load for actual bending is removed, measured by the bending angle measuring device is not within a tolerance relative to the object flange dimension, so as to put the measured flange dimension within the tolerance.
Thus, if the flange dimension in the actual bending is not within the tolerance which is a permissible range relative to the object flange dimension, the correction value calculating means sets up the correction L value and carries out the corrective bending.
According to yet another aspect of the present invention, a bending system is provided wherein a high-level NC apparatus includes the three-dimensional stereoscopic diagram creating means and the major dimension display means and a low-level NC apparatus includes the test piece display means, the bending angle measuring device, the spring back amount setting means, the object stroke calculating means, the flange dimension measuring device and the correction value calculating means, the low-level NC apparatus belonging to a bending machine.
Thus, the three-dimensional stereoscopic diagram creating means and major dimension display means, provided on the high-level NC apparatus, create the three-dimensional stereoscopic diagram and at the same time, displays the major dimension. On the other hand, the test piece display means, the bending angle measuring device, the spring back amount setting means, the object stroke calculating means, and the flange dimension measuring device, provided on the low level NC apparatus, carry out the trial bending on the test piece and measure the bending angles and flange dimensions before and after the bending load is removed. Further, the spring back amount and elongation amount are calculated so as to set up the object D value and the object L value. If there is a necessity, the correction D value and the correction L value are set up so as to execute the corrective bending.